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Overview of Contraception

By Laura Sech, MD, Family Planning Fellow, Department of Obstetrics and Gynecology, University of Southern California Keck School of Medicine
Daniel R. Mishell, Jr., MD, MSc, Endowed Professor of Obstetrics and Gynecology, Keck School of Medicine, University of Southern California
Emily Silverstein, MD, Research Project Manager, Department of Obstetrics and Gynecology, University of Southern California Keck School of Medicine

Contraception is prevention of fertilization of an egg by a sperm (conception) or prevention of attachment of the fertilized egg to the lining of the uterus (implantation).

Did You Know...

  • The effectiveness of certain contraceptive measures, such as the pill or rhythm methods, depends a great deal on how well instructions are followed.

There are several methods of contraception. None is completely effective, but some methods are far more reliable than others. Effectiveness often depends on how closely people follow instructions. Following instructions for some methods is easier than for others. Thus, the difference in effectiveness between typical use (how most people use it), which is often inconsistent, and perfect use (following the instructions exactly) may vary greatly from one method to another. For example, oral contraceptives are very effective with perfect use. However, many women forget to take some doses. Thus, average use of oral contraceptives is much less effective than perfect use. In contrast, contraceptive implants, once inserted, require nothing more (and are thus used perfectly) until they need to be replaced. Thus, typical use is the same as perfect use (until implants need to be replaced). People tend to follow instructions more closely as they get used to using a method. As a result, the difference between effectiveness with perfect use and that with typical use often decreases as time passes.

How Effective Is Contraception?


Percentage of Women Who Become Pregnant During the First Year of Use*

Perfect Use

Typical Use

Hormonal methods (with estrogen and/or a progestin)

Oral contraceptives



Implant inserted under the skin


Same as perfect use

Skin patch



Vaginal ring



Injection of medroxyprogesterone acetate (a progestin)



Barrier contraceptives


2% with male condoms

5% with female condoms

18% with male condoms

21% with female condoms

Diaphragm with spermicide



Contraceptive sponge/cervical cap

9% for women who have not had children

20% for women who have had children

12% for women who have not had children

24% for women who have had children

Other methods

Intrauterine device (IUD)

0.2% or 0. 3–0.5% with levonorgestrel-releasing IUDs, depending on the type used

0.6% with copper IUDs

Same as perfect use

Fertility awareness (rhythm) methods

4% or higher, depending on the method


Withdrawal method



*About 85% of women become pregnant during 1 year of frequent intercourse if no contraception is used.

Besides its degree of effectiveness, each contraceptive method has other advantages and disadvantages. For example, hormonal methods have certain side effects, which may increase or decrease women’s risk of developing certain disorders, including cancer of the ovary or uterus. Choice of method depends on lifestyle, preferences, and the degree of reliability needed.

Comparing Contraceptive Methods



Side Effects

Other Considerations

Hormonal methods

Oral contraceptives

Daily action is usually required.

With combination oral contraceptives (estrogen plus a progestin), a woman typically takes the contraceptive every day for 3 weeks, followed by an inactive tablet every day for 1 week.

Progestin-only oral contraceptives are taken every day at the same time of day.

A visit to the doctor is required periodically to have the prescription renewed.

Irregular bleeding (usually only during the first few months of use)

Nausea, bloating, fluid retention, increased blood pressure, breast tenderness, headaches, and weight gain

Increased risk of blood clots

Women who are older than 35 and who smoke should not take oral contraceptives.

Certain disorders also prohibit their use (see Table: When Taking Combination Oral Contraceptives Is Prohibited*).

Women who take oral contraceptives are less likely to have menstrual cramps, premenstrual dysphoric disorder (a severe form of premenstrual syndrome), acne, and irregular bleeding. They are also are less likely to develop osteoporosis and several types of cancer.

Implant under the skin

Implants require action only once every 3 years.

A doctor inserts a small rod that contains a progestin under the skin of the inner arm.

Irregular or no menstrual periods during the first year

Headaches and weight gain

Restrictions for use are generally less than those for contraceptives that contain estrogen.

An incision is required to remove implants.

Skin patch

Women apply a new patch every week for 3 weeks, then remove it and leave it off for 1 week.

A visit to the doctor is required periodically to have the prescription renewed.

Similar to those of oral contraceptives

Skin irritation at the application site

Restrictions are similar to those of oral contraceptives.

Vaginal ring

Women insert a ring once every 3 weeks, then remove it and not use it for 1 week. Or they may leave the ring in place for 4 or even 5 weeks, then remove it and replace it with a new one. A new ring is used each time.

A visit to the doctor is required periodically to have the prescription renewed.

Generally similar to those of oral contraceptives, except that irregular bleeding is typically less frequent with the ring

Restrictions are similar to those of oral contraceptives.

During the first week of use, a backup method of birth control should be used.

Rings may be expelled. If they are expelled and then reinserted within 3 hours, no backup method of birth control is needed.

Injection of medroxyprogesterone acetate (a progestin)

An injection is given by a doctor every 3 months.

Irregular bleeding (which becomes less frequent with time) or no menstrual periods while injections are being used

Weight gain, headache, and a temporary decrease in bone density

This method reduces the risk of uterine (endometrial) cancer, pelvic inflammatory disease, and iron deficiency anemia.

Barrier methods


Men apply a condom immediately before every act of sexual intercourse.

Condoms for women are inserted into the vagina, and the penis is carefully guided into the condom.

Condoms are discarded after one use.

Condoms are available over the counter.

Allergic reactions and irritation

Condoms provide protection against common sexually transmitted diseases. Latex condoms protect against human immunodeficiency virus (HIV).

Condoms must be used correctly to be effective.

This method requires diligence and cooperation by the sex partner.

Diaphragm with a spermicidal cream or gel (which kills sperm)

Women insert a diaphragm before sexual intercourse. The diaphragm should be left in place for at least 6 to 8 hours and may be left in place for up to 24 hours. A doctor fits the diaphragm and checks the fit at least once a year and after childbirth.

The spermicidal cream or gel used with a diaphragm may make insertion messy.

Allergic reactions, irritation, and urinary tract infections

After initial insertion of the diaphragm, additional cream or gel should be inserted into the vagina before each act of intercourse.

Cervical cap

Women may insert a cervical cap up to 40 hours before sexual intercourse. They must leave it in place for at least 6 hours after intercourse, but it should not stay in place for longer than 48 hours.

Allergic reactions and skin irritation

This method cannot be used during menstruation.

Contraceptive sponge

Women insert the sponge before sexual intercourse. The sponge can be inserted in advance and is effective for 24 hours. It is discarded after one use.

Sponges are available over the counter.

Allergic reactions and vaginal dryness or irritation

Sponges may be difficult to remove. They must be removed after 30 hours.

Sponges are less effective than diaphragms.

Other methods

Intrauterine device (IUD)

IUDs require action only once every 3, 5, or 10 years, depending on the type used.

IUDs are inserted and removed by a doctor.

Bleeding and/or pain

Rarely, perforation of the uterus

Occasionally, the IUD is expelled.

Fertility awareness (rhythm) methods

Women keep track of their fertile days by

  • Using a calendar

  • Checking their cervical mucus almost every day

  • Checking their cervical mucus plus body temperature and other symptoms almost every day


This method requires diligence by women and abstinence from sexual intercourse several days a month. It is less effective for women with irregular menstrual cycles.

Withdrawal method

Men withdraw their penis from the vagina before ejaculation.

Self-control and precise timing are required.


This method is less effective than other methods because sperm may be released before ejaculation and because the man may not withdraw before ejaculation.

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